.Layout_demo3{
    .logo{
        width: 120px;
        height: 31px;
        background: rgba(255, 255, 255, 0.2);
        margin: 16px 24px 16px 0;
        float: left;
    }
    .site-layout-content{
        background: #fff;
        padding: 24px;
        min-height: 280px;
    }
    .site-layout-background{
        background: #fff;
    }
}